Recorders, for example video recorders, are known in which a rotating head wheel is enclosed wholly or partially by a magnetic tape. The head wheel is equipped with one or a plurality of heads which record tracks on the magnetic tape in a helical, transversal or parallel orientation relative to the edge of the tape.
In certain recorders, the prescribed process of recording successive tracks or other special modes of operation require the head wheel to be displaced in the direction of the axis of rotation. Such an axial displacement is required, for example, in matrix recording on tracks that extend parallel to the edge of the tape as disclosed in German Patent Application No. P 35 09 584. The axial displacement may also serve to shift the head wheel into another region of the magnetic tape. This is appropriate, for example, if, according to German Offenlegungsschrift [laid-open patent application] No. 3,307,324, two or more groups of tracks containing different signals are recorded on the magnetic tape. The axial displacement is also required in a recorder operating with helical track recording in which, according to German Patent Application No. P 35 17 317, special modes of tape movement require the shifting of the head wheel in the direction of its axis. It has previously been proposed to bring about such axial displacement of the head wheel by means of a cam which acts axially on the head wheel, by means of a dipper coil, an actuator, or by means of a stepping motor.
The prior art solutions for such lifting movement have various drawbacks. These drawbacks include, among other things, a lack of mechanical accuracy in that, a play developes upon the reversal of the axial displacement due to the relatively large mass to be reversed and the dependence on gravity.